## Constraint Propagation for Linear Recursive Rules (1993)

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Citations: | 5 - 2 self |

### BibTeX

@MISC{Harland93constraintpropagation,

author = {James Harland and Kotagiri Ramamohanarao},

title = {Constraint Propagation for Linear Recursive Rules},

year = {1993}

}

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### Abstract

There are many ways in which the query answering process for deductive databases may be optimised. Many of these methods rely on applying constraints as soon as possible, to avoid the production and later rejection of facts which are not relevant to the query. This propagation of constraints is much simpler for left-linear programs than for many others. In this paper we show how to transform right-linear and mixed-linear programs into a left-linear form, to make constraint propagation more effective. Our technique generalises the magic set transformation for linear programs; the magic set transformation can only propagate constraints of the form X = a, whereas our technique can handle arbitrary goals as constraints.

### Citations

1855 |
Foundations of Logic Programming
- Lloyd
- 1987
(Show Context)
Citation Context ...gnificance of this class of programs in the next section. We will also need to make use of the well known T P operator. For completeness, we give the definition below; further details may be found in =-=[4]-=-. Definition 2.6 Let P be a program. We define an operator T P mapping sets of atoms to sets of atoms as follows: T P (I) = fA j there is an instance A :- B 1 ; : : : B n of a clause in P such that B ... |

298 | Magic Sets and Other Strange Ways to Implement Logic Programs - Bancilhon, Maier, et al. - 1986 |

213 |
Unfold/fold transformations of logic programs
- Tamaki, Sato
- 1984
(Show Context)
Citation Context ...us a general technique, such as the one given in this paper, would be supplemented by certain specialised methods of constraint propagation. A particular case in which the fold/unfold transformations =-=[9, 8]-=- may be of use is when the constraints are not explicitly given. For example, consider the goal ?- t 1 (X; Y ); t 2 (Y; Z) where t 1 and t 2 are two different transitive closure programs. Clearly ther... |

82 |
Implementation of Logical Query Languages for Data Bases
- Ullman
- 1985
(Show Context)
Citation Context ...r), the propagation of constraints in the manner described herein seems worthwhile. It should be noted that linear programs are an important class, and have been the subject of much study in the past =-=[6, 7, 10]-=-. For this reason, efficient query evaluation for such programs is an important issue, and in this paper we have attempted to give a maximally general method of constraint propagation for this class o... |

61 | Alpha: An Extension of Relational Algebra to Express a Class of Recursive Queries - Agrawal - 1988 |

26 | Argument Reduction by Factoring - Naughton, Ramakrishnan, et al. - 1989 |

26 | Direct algorithms for computing the transitive closure of database relations - Agrawal, Jagadish - 1987 |

8 | On the Power of - Beeri, Ramakrishnan - 1987 |

6 | Overbound and Right-Linear Queries
- Mumick, Pirahesh
- 1991
(Show Context)
Citation Context ...is paper we show transformation process for right-, mixed-, and multi-linear programs. Our method applies not just to binding constraints, but to any constraint, unlike the context transformations of =-=[3, 5]-=-. Thus we arrive at a general and powerful method of constraint propagation. In particular, the optimization of the magic set transformation for right-linear programs of [6] is a particular instance o... |

6 | Hybrid transitive closure algorithms - Agrawal, Jagadish |

3 |
Efficient Evaluation of Right
- Naughton, Ramakrishnan, et al.
- 1989
(Show Context)
Citation Context ...xample, consider the query ?- t(1; Y ) for the program below. t(X; Y ) :- p(X; Y ). t(X; Y ) :- p(X; Z); t(Z; Y ). The magic set transformation for the adornment bf , together with the refinements of =-=[6]-=- produces the program and query below. ?- ft(Y ). ft(Y ) :- m(X); p(X; Y ). m(Z) :- m(X); p(X; Z). m(1). Note that the original program is right-linear for the adornment bf , because in the natural ev... |

2 |
Multi-linear Rule Transformations which Maintain Context
- Kemp, Ramamohanarao, et al.
- 1990
(Show Context)
Citation Context ...is paper we show transformation process for right-, mixed-, and multi-linear programs. Our method applies not just to binding constraints, but to any constraint, unlike the context transformations of =-=[3, 5]-=-. Thus we arrive at a general and powerful method of constraint propagation. In particular, the optimization of the magic set transformation for right-linear programs of [6] is a particular instance o... |

2 |
Deterministic Transformation and Deterministic Synthesis
- Sato, Tamaki
- 1988
(Show Context)
Citation Context ...us a general technique, such as the one given in this paper, would be supplemented by certain specialised methods of constraint propagation. A particular case in which the fold/unfold transformations =-=[9, 8]-=- may be of use is when the constraints are not explicitly given. For example, consider the goal ?- t 1 (X; Y ); t 2 (Y; Z) where t 1 and t 2 are two different transitive closure programs. Clearly ther... |

1 | Constraints for Query Optimization in Deductive Databases
- Harland, Ramamohanarao
- 1992
(Show Context)
Citation Context ... are large and the intersection of them small, then there is will be a significant benefit in propagating such a constraint. A method for doing this, based on fold/unfold transformations was given in =-=[1]; essentia-=-lly the "domain" constraint is propagated into t 1 . Clearly such methods will be useful in a general constraint propagation package. It is important to note that the particular transformati... |